GPS Control Network Optimization Technology And Coordinate Transformation Study

This dissertation presents the optimization technology research on the estimation of GPS control network. Some problems on coordinate transformation are also studied. The main achievements of this paper are as follows:1. The guidelines which assess baseline solution quality are summarized, after analyzing the effects of the mode of GPS baseline solution, troposphere model selection and GPS ephemeris on baseline quality, some useful conclusions are obtained.2. By analyzing the major factors that influence baseline solution quality, the paper demonstrates the technology and method on baseline optimization according to actual example.3. The relation between observation period and GPS control network quality is studied. The results indicate increasing observation period may not only improve the precision and reliability of GPS control network but also improve the stability of GPS baseline value as a whole. However, as for individual GPS baseline, the effect of increaseing observation period on baseline result possesses indetermination because of encountering all kinds of errors. For national C level GPS network, using double frequency receiver, the quality of GPS network may attain demand when observation period is more than one hour.4. The key of estimating GPS point accuracy is an estimate of baseline covariance. This paper computes lots of baselines of certain GPS control network using Pinnacle software in Xining area. The inherent relation of GPS baseline covariance is sought by analyzing a great deal of GPS baseline result and an inherent relation equation of baseline covariance is fitted. An actual measure GPS control network is analyzed using the equation. Result show that the GPS point precision may be well estimated.5. To study the affection of scale parameters on coordinate transformation , seven-parameters model and nine-parameters model is used to transform VLBI and GPS data respectively. The result shows that the real accuracy of VLBI and GPS geocentric coordinates is within 1cm, and the scale deflection of VLBI and GPS techniques is very little, the result using seven-parameter model to process coordinate transformation is better.6. There are bigger rolling parameter between WGS-84 coordinate system and local independency coordinate system frequently. In allusion to this case, this paper analyse the magnitude that rolling parameter influence the linearization coordinate transformation model, and put forward a new method utilizing Rosenbrock Method to resolve rolling parameter. The results processing simulation data indicate, the method may effectively weaken model error and improve precision of coordinate transformation.